Now box 2d lets you move the box around with right and left mouse buttons.

sfmldemo/main.cpp

@@ -1,7 +1,7 @@
 #include "imgui.h"
 #include "imgui-SFML.h"
 #include <fmt/core.h>
-
+#include <box2d/box2d.h>
 #include <SFML/Graphics/CircleShape.hpp>
 #include <SFML/Graphics/RenderWindow.hpp>
 #include <SFML/System.hpp>
@@ -35,22 +35,55 @@ void Window_update(sf::RenderWindow &window, sf::Shape &shape) {
     window.display();
 }
 
+struct BoxTest {
+  b2Body *groundBody;
+  b2Body *body;
+};
+
+struct BoxTest Box2d_setup(b2World &world) {
+  b2BodyDef groundBodyDef;
+  groundBodyDef.position.Set(0.0f, -10.0f);
+  b2Body *groundBody = world.CreateBody(&groundBodyDef);
+
+  b2PolygonShape groundBox;
+  groundBox.SetAsBox(50.0f, 10.0f);
+  groundBody->CreateFixture(&groundBox, 0.0f);
+
+  b2BodyDef bodyDef;
+  bodyDef.type = b2_dynamicBody;
+  bodyDef.position.Set(3.0f, 4.0f);
+  b2Body *body = world.CreateBody(&bodyDef);
+
+  b2PolygonShape dynamicBox;
+  dynamicBox.SetAsBox(1.0f, 1.0f);
+  b2FixtureDef fixtureDef;
+  fixtureDef.shape = &dynamicBox;
+
+  fixtureDef.density = 1.0f;
+  fixtureDef.friction = 0.3f;
+
+  body->CreateFixture(&fixtureDef);
+
+  BoxTest box {groundBody, body};
+  return box;
+}
+
 int main() {
   fmt::print("Setting up a window for you...\n");
   sf::ContextSettings settings;
   settings.antialiasingLevel = 8;
 
-  sf::RenderWindow window(sf::VideoMode(1920, 1080), "Simple Game Demo", sf::Style::Default, settings);
+  sf::RenderWindow window(sf::VideoMode(720, 480), "Simple Game Demo", sf::Style::Default, settings);
 
   // window.setFramerateLimit(60);
   window.setVerticalSyncEnabled(true);
 
   ImGui_setup(window);
 
-  sf::CircleShape shape(100.f, 4);
-  sf::Vector2u size = window.getSize();
-  shape.setPosition(size.x / 2, size.y / 2);
-  shape.setOrigin(100.f, 100.f);
+  sf::CircleShape shape(50.f, 4);
+  sf::Vector2u winSize = window.getSize();
+  shape.setPosition(winSize.x / 2, winSize.y / 2);
+  shape.setOrigin(50.f, 50.f);
   shape.setFillColor(sf::Color(150, 50, 250));
   shape.setOutlineThickness(10.f);
   shape.setOutlineColor(sf::Color(250, 150, 100));
@@ -69,6 +102,14 @@ int main() {
 
   thread.launch();
 
+  b2Vec2 gravity(0.0f, -10.0f);
+  b2World world(gravity);
+  BoxTest box = Box2d_setup(world);
+
+  float timeStep = 1.0f / 60.0f;
+  int velocityIterations = 6;
+  int positionIterations = 2;
+
   while (window.isOpen()) {
     sf::Event event;
 
@@ -96,8 +137,11 @@ int main() {
           break;
         case sf::Event::MouseButtonPressed:
           if(sf::Mouse::isButtonPressed(sf::Mouse::Left)) {
-            sf::Vector2i clickAt = sf::Mouse::getPosition(window);
-            shape.setPosition(clickAt.x, clickAt.y);
+            b2Vec2 force(-200, 1000);
+            box.body->ApplyForceToCenter(force, true);
+          } else if (sf::Mouse::isButtonPressed(sf::Mouse::Right)) {
+            b2Vec2 force(200, 1000);
+            box.body->ApplyForceToCenter(force, true);
           }
           break;
       }
@@ -110,8 +154,13 @@ int main() {
       tick = since;
     }
 
+    world.Step(timeStep, velocityIterations, positionIterations);
+    b2Vec2 position = box.body->GetPosition();
+    float angle = box.body->GetAngle();
+
+    shape.setPosition(position.x * 100.0f, winSize.y - position.y * 100.0f);
+    shape.setRotation(angle * 180.0f / M_PI);
 
-    shape.rotate(1);
 
     ImGui_update(window, deltaClock, tick);
     Window_update(window, shape);

sfmldemo/meson.build

@@ -5,6 +5,7 @@ dependencies = [
   dependency('sfml'),
   dependency('imgui-sfml'),
   dependency('fmt'),
+  dependency('box2d'),
 ]
 
 executable('sfmldemo', 'main.cpp',

sfmldemo/reset_build.ps1

@@ -14,4 +14,5 @@ meson wrap install sfml
 meson wrap install vorbis
 meson wrap install zlib
 meson wrap install fmt
+meson wrap install box2d
 meson setup -Ddefault_library=static builddir

sfmldemo/reset_build.sh

@@ -17,4 +17,5 @@ meson wrap install sfml
 meson wrap install vorbis
 meson wrap install zlib
 meson wrap install fmt
+meson wrap install box2d
 meson setup builddir

sfmldemo/setup.ps1

@@ -10,4 +10,5 @@ meson wrap install openal-soft
 meson wrap install sfml
 meson wrap install vorbis
 meson wrap install zlib
+meson wrap install box2d
 meson setup -Ddefault_library=static builddir

sfmldemo/setup.sh

@@ -0,0 +1,18 @@
+#!/usr/bin/env bash
+set -ex
+
+mkdir subprojects
+mkdir builddir
+meson wrap install flac
+meson wrap install freetype2
+meson wrap install imgui-sfml
+meson wrap install imgui
+meson wrap install libpng
+meson wrap install ogg
+meson wrap install openal-soft
+meson wrap install sfml
+meson wrap install vorbis
+meson wrap install zlib
+meson wrap install fmt
+meson wrap install box2d
+meson setup builddir